The present invention relates to a component arrangement comprising a semiconductor component and a temperature measuring arrangement, and to a method for determining the temperature in a semiconductor component, in particular for determining the temperature at a point that is hottest during the operation of the component, the so-called “hot spot” temperature.
During operation of semiconductor components, the power loss that is inevitably incurred leads to the heating of the semiconductor component. Said heating is all the greater, the more power is converted in the semi-conductor component. This evolution of heat is critical particularly in the case of power components, such as power transistors, for example, which are designed to switch voltages of up to a few hundred volts in conjunction with currents of corresponding magnitude. Such power transistors are used for example for driving loads in output stages and switching stages for industrial electronics and automotive engineering.
The temperature of a semiconductor component, in particular of a power semiconductor component, constitutes a significant parameter to be monitored during operation. An excessively high temperature of the component, which is caused for example by an increased ambient temperature, by a malfunction of the semiconductor component or by a malfunction of a connected load, may lead to damage or destruction of the component and furthermore also to the impairment or even destruction of the load. The maximum permissible depletion layer temperature of silicon-based transistors is for example approximately 175° C. to 200° C., and that of germanium-based transistors is approximately 75° C. to 90° C. An overshooting of this temperature range leads to the destruction of the respective semiconductor component. It is therefore essential to identify a possible overtemperature of semiconductor components in good time and reliably in order to be able to implement suitable measures, such as, for example, turning off the semiconductor component or the load, before critical temperature values are reached, and thus before a damaging event occurs.
In this connection, it may be desirable not only to reliably identify the overtemperature of a semiconductor component, but also to be able to detect the respectively current temperature value of the component in real time. This enables an analysis of the temperature behavior of a circuit, for example in a manner dependent on different operating states.
In order to determine the temperature of a semi-conductor component, it is known to fit a temperature sensor on the housing of the semiconductor component or on the semiconductor body/chip itself arranged in the housing. In this case, the sensor and the actual semi-conductor component are two separate components, so that the sensor only detects the temperature externally at the semiconductor component. This external temperature may deviate considerably from the temperature within the semiconductor component, particularly when the position of the temperature sensor is far away from the position of the hottest point in the semiconductor body. What is more, temperature changes within the semiconductor body affect temperature changes in the region of the sensor only in a time-delayed fashion. However, precisely the exact detection of the temperature within the semiconductor body is relevant for determining critical operating states or the analysis of dynamic operations.
In order to determine the internal temperature of a semiconductor component, it is furthermore known to provide a temperature sensor in the same semiconductor body into which the semiconductor component is integrated. Said sensor is a diode, for example, which is operated in the reverse direction and the reverse current or reverse voltage of which is detected.
What is common to the known arrangements or methods for temperature measurement is that even in the case of integrated temperature sensors, the measured temperature is always lower than the actual peak temperature at the hottest location—also referred to as “hot spot”—of the semiconductor component. An essential reason for this is that the temperature sensor cannot be positioned directly at the position of the hot spot itself, for example at the depletion layer of a power transistor, without impairing the desired function of the semiconductor component itself. The sensor is therefore arranged at a distance from the hot spot.
Furthermore, the measurement of the temperature of a semiconductor component by means of a concomitantly integrated temperature sensor always has a temporal inertia. Particularly in the case of fast transient changes in the temperature at the hot spot of a semi-conductor component, such as occur for example when a load is turned on by means of a power transistor, a change in the temperature at the hot spot affects a temperature sensor spatially remote from said hot spot only in temporally delayed fashion. Due to a thermal capacity of the semiconductor body that is inevitably present, the thermal transfer path for the temperature between the hot spot and the temperature sensor acts like a low-pass filter. Therefore, it may, if applicable, not be possible to react rapidly enough to a rapidly occurring overtemperature of the semi-conductor component, such as by turning off or regulating back a load, for example.